The present invention relates to an adjustment mechanism for a mirror, and more particularly to an adjustment mechanism for a mirror of a liquid crystal projector.
FIG. 1 illustrates a structure of a liquid crystal projector according to prior art. The liquid crystal projector includes a light source 1, a light integrator 3, a condenser lens 4, a first dichroic mirror 5, a second dichroic mirror 6, a first liquid-crystal panel 7, a second liquid-crystal panel 8, a third liquid-crystal panel 9, a tri-color synthetic prism 10, a projection lens 11, a total reflection mirror 12, a field lens 15, a first reflection mirror 17, a second reflection mirror 18, a third reflection mirror 14 and a relay lens 21.
The light source 1 emits polychromatic light. The light integrator 3 is used for making the amount of light in the beam from the light source 1 substantially uniform in a cross section normal to the optical axis. The condenser lens 4 is used for gathering rays emitted from the light integrator 3. The first dichroic mirror 5 and the second dichroic mirror 6 are used for separating the polychromatic light into three chromatic components, i.e. a blue component, a red component and a red component. Each of the first liquid-crystal panel 7, the second liquid-crystal panel 8 and the third liquid-crystal panel 9 is used for modulating each chromatic component in response to predetermined data. The projection lens 11 is used for forming images of the rays composed at the tricolor synthetic prism 10 onto a screen (not shown). The total reflection mirror 12 is arranged on the condenser lens 4 for reflecting rays emitted from the light integrator 3, thereby directing them to the condenser lens 4.
The first dichroic mirror 5 separates the incident rays into a blue component and a remainder component composed of a green component and a red component. The second dichroic mirror 6 separates the remainder component into a green component and a red component. The red component passes through the relay lens 21 arranged between the first reflection mirror 17 and second reflection mirror 18 and is then projected onto the third liquid-crystal panel 9. The blue component is totally reflected by the third reflection mirror 14 and modulated into a parallel ray by the field lens 15 to project onto on the first liquid-crystal panel 7. The green component passes through the field lens 16 located along the optical path thereof so as to form a parallel ray and project onto the second liquid-crystal panel 8.
In the optical devices described above, only the red component has a different distance from the source 1 to the tricolor synthetic prism 10. Thus, a relay lens 21 is arranged between the first reflection mirror 17 and the second reflection mirror 18 so as to make the source 1 of the red component have equal distance as that of the blue and the green component.
However, the structure of the customarily used liquid crystal projector in FIG. 1 has the advantages of image deviations in positioning due to the tolerance of assembly or production. Referring to FIGS. 2(a) and 2(b), a tilt adjustment mechanism is built in the total reflection mirror 12 for adjusting the orientation thereof. The tilt adjustment mechanism includes a mirror supporting frame 23 for supporting a bottom edge of the mirror 12, a bottom supporting member 24 for supporting one surface of the mirror 12 near its bottom edge at the center thereof, a pair of top supporting member 25 for supporting the top edge of the mirror 12 and two springs 26 and 27 for pushing against the opposite surface of the mirror 12, thereby holding the mirror securely against the supporting members 24 and 25. The top supporting member 25 includes an adjusting plate 28, a fixing member 29 (e.g. a screw) for fixing the adjusting plate 28 to the supporting frame 23. The tilt adjustment mechanism is implemented by loosing the screw, shifting each adjusting plate 28 forward or backward relative to the mirror 12 and fixing the adjusting plate 28 to the supporting frame 23. Because the above-mentioned tilt adjustment mechanism is performed by rotating the mirror 12 via the bottom supporting member 24 as a pivot, the top edge of the mirror is always shifted more than the bottom edge. Therefore, the image deviations still could not be effectively reduced. Therefore, the present invention provides an improved mirror adjustment device for overcoming the problems described above.
It is an object of the present invention to provide an adjustment mechanism of a mirror for a liquid crystal projector for reducing image deviations due to the tolerance of assembly or production.
It is another object of the present invention to provide an adjustment mechanism of a mirror for a liquid crystal projector by rotating the mirror via a tip of a resilience sheet as a pivot.
In accordance with one aspect of the present invention, there is provided an adjustment mechanism including a supporting portion and an adjusting device. The supporting portion includes a first plate having a surface in contact with the mirror, a second plate connected with the top edge of the first plate and a resilience sheet disposed between the first plate and a housing of the projector. The adjusting device passes through a hole of the second plate to be in contact with the housing and is capable of being adjusted for rotating the mirror.
Preferably, the projector is a liquid crystal projector.
Preferably, the mirror is one of a reflection mirror and a total reflection mirror.
Preferably, the second plate is L-shaped.
Preferably, the resilience sheet has two ends connected with the housing and a tip in contact of the center of the first plate.
Preferably, the resilience sheet is in a shape of an arc, wherein the tip of the arc is in contact with the center of the first plate.
Preferably, the adjusting device is a screw.
In accordance with another aspect of the present invention, there is provided an adjustment mechanism for adjusting a mirror of a liquid crystal projector. The adjustment mechanism includes a first plate having a surface in contact with the mirror, a second plate connected with the top edge of the first plate, a resilience sheet disposed between the first plate and a housing of the projector and has two ends connected with the housing and a tip in contact of the center of the first plate, and a screw passing through a hole of the second plate to be in contact with the housing and capable of be adjusted for rotating the mirror via the tip as a pivot.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: